import com.intellij.openapi.actionSystem.AnAction;
import com.intellij.openapi.actionSystem.AnActionEvent;
import com.intellij.openapi.application.Application;
import com.intellij.openapi.application.ApplicationManager;
import com.intellij.openapi.ui.Messages;

public class HelloWorld extends AnAction {

    @Override
    public void actionPerformed(AnActionEvent e) {
        // TODO: insert action logic here
        Messages.showMessageDialog(
                "Hello World!",
                "Sample",
                Messages.getInformationIcon()
        );
    }
}